1. Field of the Invention
This invention relates to an imaging method and apparatus for forming an image of an object supported in a casing. This invention also relates to an image processing method and apparatus for the imaging method and an imaging system comprising the imaging apparatus.
2. Description of the Related Art
Imaging apparatuses, in which an object is supported in a casing, light having been produced by a light source located within the casing is irradiated to the object, and an image of the object is thus formed, have heretofore been used in various fields. For example, in fields of biochemistry, fluorescence detecting systems utilizing a fluorescent substance as a labeling substance have heretofore been known. With the fluorescence detecting systems, analyses of gene sequences and gene expression levels, separation and identification of proteins, and evaluation of molecular weights and characteristics are capable of being performed in accordance with information obtained by reading out fluorescence images.
Specifically, for example, after a fluoro chrome has been added to a liquid containing a plurality of DNA fragments to be subjected to electrophoresis, electrophoresis of the plurality of the DNA fragments may be performed on a gel support. Alternatively, electrophoresis of a plurality of DNA fragments may be performed on a gel support containing a fluoro chrome. As another alternative, after electrophoresis of a plurality of DNA fragments has been performed on a gel support, the DNA fragments having been subjected to the electrophoresis may be leveled with a fluoro chrome by, for example, a process for dipping the gel support in a liquid containing the fluoro chrome, the fluoro chrome may then be excited with excitation light to produce fluorescence, the thus produced fluorescence may be detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a DNA distribution on the gel support is capable of being detected.
As a further alternative, after electrophoresis of a plurality of DNA fragments has been performed on a gel support, the DNA fragments having been subjected to the electrophoresis may be denatured. Thereafter, at least part of the denatured DNA fragments maybe transcribed to a transcription support, such as nitrocellulose, with a Southern blotting technique. The denatured DNA fragments and a probe having been prepared by labeling a DNA or an RNA, which is complementary to a target DNA, with a fluoro chrome, may then be subjected to hybridization. In this manner, only a DNA fragment, which is complementary to the probe DNA or the probe RNA, is selectively labeled with the fluoro chrome. Thereafter, the fluoro chrome, with which the DNA fragment described above has been labeled, may be excited with the excitation light to produce the fluorescence, the thus produced fluorescence may be detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a target DNA distribution on the transcription support is capable of being detected.
Recently, micro array analysis systems utilizing micro arrays have attracted particular attention as biochemical analysis systems. By way of example, with the micro array analysis systems utilizing a fluorescent substance as a labeling substance, a micro array is prepared by, for example, spotting multiple kinds of specific binding substances, which are capable of specifically binding to organism-originating substances and whose base sequences, base lengths, compositions, and the like, are known, onto different positions on a surface of a carrier, such as a slide glass plate or a membrane filter, by use of a spotting apparatus and thereby forming a plurality of independent spots on the surface of the carrier. Examples of the specific binding substances include hormones, tumor markers, enzymes, antibodies, antigens, abzymes, other proteins, nucleic acids, cDNA's, DNA's, and RNA's. Thereafter, an organism-originating substance, which has been sampled from an organism through extraction, isolation, or the like, or has been subjected to chemical treatment, chemical modification treatment, or the like, and which has been labeled with a fluorescent labeling substance, such as a fluorescent substance or a fluoro chrome, is subjected to hybridization with the specific binding substances, which have been fixed to the spots on the micro array. The organism-originating substance is thus specifically bound to one of the specific binding substances on the micro array. Examples of the organism-originating substances include hormones, tumor markers, enzymes, antibodies, antigens, abzymes, other proteins, nucleic acids, cDNA's, DNA's, and mRNA's. Excitation light is then irradiated to the micro array, and the fluorescence produced by the labeling substance, such as the fluorescent substance or the fluoro chrome, with which the organism-originating substance has been labeled, is photoelectrically detected. In accordance with the results of the photoelectric detection, the organism-originating substance is analyzed.
In the biochemical analysis systems described above, an imaging apparatus comprising an excitation light source and a CCD image sensor, which are located in a casing, is utilized in order to detect the fluorescence, or the like. Also, the micro array described above, a gel, or the like, acting as a sample is accommodated in the casing, and excitation light having been produced by the excitation light source is irradiated to the sample in order to excite the sample to produce the fluorescence. An image of the thus produced fluorescence is formed with the CCD image sensor acting as imaging means.
Besides the imaging apparatuses utilized in the biochemical analysis systems, there have heretofore been known imaging apparatuses, in which an object is accommodated in a casing provided with a light source, light having been produced by the light source is irradiated to the object, and an image of the object is formed with an imaging section. The imaging apparatuses have a structure, such that the position of the light source for producing the light (or excitation light) is fixed at a predetermined position.
However, sizes of the objects whose images are to be formed take various values. Therefore, the conventional imaging apparatuses are constituted such that an object is capable of being located at one of various different height positions in accordance with the size of the object. Specifically, the object is supported by a sample tray having an approximately plate-like shape, the sample tray is held at one of stages of a tray holding section, which stages are located within the casing, and an imaging operation is performed in this state. In this manner, images of objects having different sizes are capable of being formed with the imaging means.
However, in cases where the position of the object is altered, while the position of the light source is being fixed at the predetermined position, the intensity of the light irradiated from the light source to the object, the distribution of illuminances of the light, and the like, vary in accordance with the position at which the object is located. Therefore, the problems occur in that the image quality of the thus formed image is affected adversely. Specifically, in cases where the imaging distance between the object and the light source is altered, the angle of incidence of the excitation light upon the object varies, and the intensity of the excitation light impinging upon the object varies. Therefore, the problems occur in that, in cases where the imaging distance is altered, image information is acquired under different imaging conditions.
Also, in cases where the obtained image information is subjected to a shading correction, the problems occur in that, since the imaging conditions vary for different imaging distances, correcting conditions must be set for each of different object heights.